Thanks, Bruce. Does the math expression in IFEFFIT include the term -4k*sigma2*(1/labmda +1/R) in the phase? If yes, the 1st cumulant is sigma1= R+dR. If no, sigma1= R+dR+2*sigma2*(1/labmda +1/R). It this correct?
Yuan On 4/1/11 2:18 PM, "Bruce Ravel" <bra...@bnl.gov> wrote: > On Friday, April 01, 2011 05:03:17 pm Ping, Yuan wrote: >> Dear IFEFFIT experts: >> >> Is it possible to add a k^3 term in the phase for fitting to take into >> account anharmonic effect? The fitted coefficient will be proportional to >> the 3rd cumulant of Debye-Waller factor. I work with high-temperature >> high-pressure systems where anharmonic effect is not negligible. >> >> Thanks. >> Yuan Ping > > > Hi Yuan, > > Here is the relevant page from the Ifeffit reference manual: > > http://cars9.uchicago.edu/~ifeffit/refman/node51.html > > You want to use the "3rd" path parameter, which adds a term > proportional to C3*k^3 to the sine function in the exafs equation. > > See the attached figure for the place in Artemis where this parameter > is introduced. > > HTH, > B _______________________________________________ Ifeffit mailing list Ifeffit@millenia.cars.aps.anl.gov http://millenia.cars.aps.anl.gov/mailman/listinfo/ifeffit